Fatal anaphylaxis to indoor native fire ant stings in an infant.

The red (Solenopsis invicta) and black (Solenopsis richteri) imported fire ants (IFA) are a common cause of venom allergy in the southeastern United States. Hypersensitivity to stings of native fire ants is less common, although anaphylaxis has been reported to various native Solenopsis species. There have been numerous reports of indoor stings caused by IFA, including in nursing homes and private residences. The following is a report of fatal anaphylaxis to a native fire ant sting in an infant that occurred indoors at a daycare facility. A 3-month-old female was left unattended on a bed. The caregiver had heard the child crying, but attributed this to colic. A short time later, the caregiver found the child apneic and covered with ants. Emergency medical services were summoned, and resuscitation attempts were unsuccessful. Postmortem examination revealed approximately 40 erythematous lesions without pustules. Examination of the respiratory system was notable for congested parenchyma and mild laryngeal edema. Laboratory studies revealed an elevated tryptase of 23.9 ng/mL and radioallergosorbent test (RAST) of 1.4% specific IgE antibody binding to Solenopsis richteri venom. RAST for specific IgE antibody binding to Solenopsis invicta venom was negative. Ants recovered from the scene were identified by an entomologist as Solenopsis xyloni, a native fire ant endemic to the southwestern United States. Native fire ants have features that distinguish them from IFA. Some native species do not build mounds, and stings may not result in pustules characteristic of IFA. There is significant cross-reactivity among the venoms of Solenopsis species, although some species' specificity exists for the Sol 2 allergen. Testing and treatment with IFA whole-body extract is likely to be to be effective for native fire ant allergy. A mixture of S. invicta and S. richteri extracts should be considered when native fire ant species are presumed to cause the primary sensitization to reduce the chance that species-specific reactivity is missed.

Identification of allergens in the venom of the common striped scorpion.

BACKGROUND: The common striped scorpion, Centruroides vittatus, is endemic to the southwestern United States and causes thousands of human stings annually. Immediate hypersensitivity reactions to C. vittatus venom have been reported. OBJECTIVES: To identify specific IgE in 11 patients with immediate hypersensitivity to C. vittatus and to characterize the allergens present in the venom. METHODS: Skin testing to dialyzed, filtered venom was performed in 5 patients. Immunoglobulin E immunoblots to whole milked venom was accomplished with serum samples from 8 patients. Enzymatic properties of whole venom were also determined. RESULTS: C. vittatus venom was found to contain 150 microg/microL of protein. Four of 5 patients tested had positive skin test reactions to the purified venom extract, with no late reactions. In all 8 patients, sodium dodecyl sulfate-polyacrylamide gel electrophoresis demonstrated multiple proteins, 9 of which were identified as allergens on IgE immunoblots, ranging in size from 30 to 170 kD. Enzymatic activity was found to include phospholipase A, alkaline phosphatase, esterase, esterase lipase, and acid phosphatase. CONCLUSIONS: C. vittatus envenomation may result in immediate hypersensitivity reactions in susceptible individuals. Venom specific IgE can be identified by using skin tests and IgE immunoblots. The allergens identified in these patients had molecular weights distinct from those of known scorpion neurotoxins. A safe and effective skin testing extract can be prepared from dialyzed pure venom and may lead to the widespread ability to diagnose C. vittatus venom allergy.

Cross-reactivity between allergens in the venom of the common striped scorpion and the imported fire ant.

BACKGROUND: The common striped scorpion, Centruroides vittatus, and the imported fire ant (IFA) are endemic to the south-central United States. There is evidence of venom-specific IgE in patients experiencing hypersensitivity reactions to scorpion stings. The infrequency of repeated scorpion stings and the presence of immediate reactions to an initial sting suggest prior sensitization. OBJECTIVE: In the present study we evaluated the cross-reactivity of C vittatus venom with IFA whole-body extract (WBE). METHODS: Sera were obtained from patients with symptoms of immediate hypersensitivity to C vittatus stings and from scorpion sting-naive patients allergic to IFA venom. Inhibition IgE immunoblots were performed by using scorpion venom and IFA WBE. Skin testing with scorpion venom was performed on scorpion sting-naive patients allergic to IFA venom. RESULTS: Sera from patients with scorpion venom allergy demonstrated IgE binding to multiple allergens of similar sizes against both scorpion venom and IFA WBE. This binding was completely inhibited by preincubation of the sera with scorpion venom and IFA WBE. Pooled sera from patients with IFA venom allergy demonstrated similar bands on IgE immunoblotting against both IFA WBE and scorpion venom, with the latter being completely inhibited by preincubation of the sera with IFA WBE. Skin testing with scorpion venom was positive in 6 of 9 patients with IFA venom allergy. CONCLUSION: Significant cross-reactivity exists between the venom of C vittatus and IFA WBE. The high sensitization rate to IFA venom in endemic areas may therefore be a risk factor for subsequent immediate reactions to an initial scorpion sting. Patients with immediate hypersensitivity reactions to scorpion stings may potentially benefit from immunotherapy with IFA WBE.

Cross-reactivity between coconut and hazelnut proteins in a patient with coconut anaphylaxis.

BACKGROUND: The medical literature reports few cases of severe allergic reactions to coconut. We encountered a patient with anaphylaxis to coconut and oral symptoms to tree nuts. OBJECTIVE: To identify cross-reactive antibodies between coconut and other tree nuts. METHODS: We performed commercial radioallergosorbent tests to coconut and various tree nuts using the patient's serum. Skin prick testing was performed to fresh coconut and commercial extracts of coconut, almond, Brazil nut, cashew, pecan, walnut, and hazelnut. Proteins from fresh coconut, commercial coconut extract, and tree nuts were extracted. Immunoblot and inhibition assays were performed to evaluate for cross-reacting IgE antibodies between similar-sized allergens in coconut and hazelnut. RESULTS: Positive skin test results occurred to the coconut and multiple tree nut extracts. In vitro serum specific IgE was present for coconut, hazelnut, Brazil nut, and cashew. Immunoblots demonstrated IgE binding to 35- and 50-kDa protein bands in the coconut and hazelnut extracts. Inhibition assays using coconut demonstrated complete inhibition of hazelnut specific IgE, but inhibition assays using hazelnut showed only partial inhibition of coconut specific IgE. CONCLUSIONS: Our study demonstrates the presence of cross-reactive allergens between hazelnut (a tree nut) and coconut (a distantly related palm family member). Because there are many potentially cross-reactive allergens among the tree nuts, we recommend patients with coconut hypersensitivity be investigated for further tree nut allergies.

Arrhythmogenic right ventricular dysplasia in the elderly.

Arrhythmogenic right ventricular dysplasia (ARVD) is a syndrome characterized by recurrent ventricular tachycardia. However, cases of ARVD have also presented as dilated cardiomyopathy later associated with ventricular arrhythmias. Histologically, this syndrome manifests as a fibrofatty replacement of the RV myocardium, predisposing the heart to ventricular arrhythmias. ARVD was once considered a disease of the young, but may be underrecognized in the older population. This report presents two cases of elderly men with newly symptomatic ARVD, believed to represent the oldest patients with ARVD described in the literature to date. The diagnosis of ARVD should be considered in individuals of all ages who present with a clinical syndrome consistent with ARVD and supportive evidence on ECG.

Factors affecting compliance with allergen immunotherapy at a military medical center.

BACKGROUND: Allergen immunotherapy (AIT) is a safe and effective treatment for certain allergic disorders; however, noncompliance with therapy is common. We evaluated the compliance rates among groups receiving AIT at a military medical center and identified factors affecting compliance. METHODS: The charts of the 381 actively enrolled patients in our AIT program were evaluated for patient compliance. Noncompliant patients were contacted to determine the reason for stopping therapy. Patients were then grouped by diagnosis, age, sex, military status, and schedule of AIT and evaluated for differences. RESULTS: The overall compliance rate was 77.4%. The most common reasons for noncompliance included inconvenience, precluding medical condition, and adverse systemic reaction. There were no differences in compliance rates by diagnosis or sex. Noncompliant patients were younger than compliant patients, 35.4 years versus 42.4 years (P = 0.001); however, when patients were divided into three age categories (<18, 18 to 45, and >45 years), the youngest and oldest groups were more compliant (P < 0.001). Active-duty members were less compliant than retirees and family members, 65.7% versus 83.1% and 81.4%, respectively (P = 0.004). Patients receiving a conventional schedule of AIT were more compliant than those on a rush schedule, 80.0% versus 48.4% (P < 0.001). CONCLUSIONS: Factors found to affect patient compliance with an AIT regimen at our military medical center include age, military status, and schedule of AIT. The most common reasons for noncompliance included inconvenience, precluding medical conditions, and adverse systemic reactions. Clinicians need to be aware of the factors limiting patient compliance with AIT in an attempt to maximize treatment effectiveness.